Method for data communication, system for communication and related devices

ABSTRACT

A data communication method, a communication system, and related devices are configured to establish a transaction identifier (TI) in a user equipment (UE). The data communication method includes the following steps. A mobility management entity (MME) receives a request message and obtains ability information of the UE. If the UE has an ability to access a Universal Terrestrial Radio Access Network/GSM/EDGE Radio Access Network (UTRAN/GERAN), the MME generates the TI. A communication system and related devices are also provided. Thus, the TI is effectively established in the UE, so as to ensure normal processing of the UE.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/869,699, filed on Apr. 24, 2013, which is a continuation of U.S.application Ser. No. 12/966,620, filed on Dec. 13, 2010, which is acontinuation of International Application No. PCT/CN2009/072245, filedon Jun. 12, 2009. The International application claims priority toChinese Patent Application No. 200810038984.7, filed on Jun. 13, 2008.The aforementioned patent applications are hereby incorporated byreference in their entireties.

FIELD OF THE TECHNOLOGY

The present invention relates to the field of communication technology,and more particularly to a data communication method, a communicationsystem, and related devices.

BACKGROUND OF THE INVENTION

In a Universal Mobile Telecommunication System (UMTS), the process forestablishing a Packet Data Protocol (PDP) context by a user equipment(UE) is as shown in FIG. 1.

Firstly, the UE sends an Activate PDP Context Request message containingparameters such as a Network Layer Service Access Point Identifier(NSAPI) and a Transaction Identifier (TI) to a Serving General PacketRadio Service Support Node (SGSN). The NSAPI is an identifier assignedby the UE to identify an established PDP context, and is used betweenthe SGSN and a Gateway General Packet Radio Service Support Node (GGSN).The TI is a transaction identifier assigned by the UE to identify theestablished PDP context and is used between the UE and the SGSN. Afterthe PDP context is established, the TI is recorded by the UE and theSGSN; during subsequent operations (for example, modification anddeactivation) on the PDP context, for example, in a Modify PDP Contextor Deactivate PDP Context Request message, the PDP context is associatedwith the TI instead of the NSAPI.

In a Long Term Evolved (LTE) network system, an Evolved Packet System(EPS) Bearer ID is corresponding to the NSAPI, but the identifier isassigned by a Mobility Management Entity (MME) instead of the UE, and inan NAS message between the UE and the MME, the bearer is identified bythe EPS Bearer ID, and identifier information similar to the TI does notexist.

In addition, in an R8 network, the concept of default bearer isintroduced, that is, when the UE accesses a System Architecture Evolved(SAE) network through an Evolved Universal Terrestrial Radio AccessNetwork (EUTRAN), the UE firstly establishes the default bearer, and thedefault bearer cannot be deleted, if the default bearer is deleted, adedicated bearer corresponding to the default bearer will be deleted aswell; when the UE accesses the SAE through a GSM/EDGE Radio AccessNetwork/Universal Terrestril Radio Access Network (GERAN/UTRAN), theconcept similar to the default bearer is also adopted, and the UE havingEUTRAN ability activates an interactive or background PDP context afterbeing attached to the GERAN/UTRAN.

In the prior art, the UE establishes the bearer context in the EUTRAN,and the UE and the MME identify the bearer by the EPS bearer ID. Afterthe UE moves to 2G/3G, in the subsequent operations on the PDP context,for example, updating the PDP context, for the NAS message between theUE and the SGSN, the PDP context will be identified by the TI, but TIinformation does not exist in the UE and the SGSN at this time, so thatthe process cannot normally works.

SUMMARY OF THE INVENTION

The embodiments of the present invention are directed to a datacommunication method, a communication system, and related devices, whichcan establish a TI in a UE when a bearer established in an LTE is mappedto a PDP context of a GERAN/UTRAN.

In an embodiment of the present invention provides a data communicationmethod, which includes the following contents. An MME receives a requestmessage, and obtains ability information of a UE. If the UE has anability to access a UTRAN/GERAN, the MME generates a TI.

In another embodiment of the present invention provides a datacommunication method, which includes the following contents. A defaultbearer creating request message sent by an SGSN is received. If thedefault bearer creating request message includes attribute instructioninformation, a default bearer is established according to a Quality ofService (QoS) parameter in the default bearer creating request message.

In another embodiment of the present invention provides a communicationsystem, which includes a packet data network gateway (PGW) and an MME.The PGW is configured to receive a request message resource allocationrequest message sent by the MME, determine whether to initiate bearermodification or establish a new bearer according to the request messageresource allocation request message, and send a dedicated bearercreating request message to the MME if determining to establish the newbearer. The MME is configured to receive the request message resourceallocation request message sent by a UE, forward the request messageresource allocation request message to the PGW, receive the dedicatedbearer creating request message sent by the PGW, obtain a beareridentifier according to the dedicated bearer creating request message,obtain ability information of the UE, determine whether the UE has anability to access a UTRAN or GERAN according to the ability informationof the UE, generate a TI according to the bearer identifier andaccording to a preset generation rule if the UE has the ability, andsend the TI to the UE.

In another embodiment of the present invention provides an MME, whichincludes an obtaining unit configured to obtain ability information of aUE, a receiving unit configured to receive a request message, and agenerating unit configured to generate a TI if the UE has an ability toaccess a UTRAN or GERAN.

In another embodiment of the present invention provides a UE, whichincludes an identifier receiving unit configured to receive a beareridentifier delivered by a core network element, and a UE side TIgenerating unit configured to generate a TI according to the beareridentifier and according to a preset generation rule.

The technical solutions have the following beneficial effects:

In the embodiments of the present invention, after it is determined thatthe UE has the ability to access the UTRAN or GERAN according to theobtained ability information of the UE, the TI is generated according tothe pre-assigned bearer identifier and according to the presetgeneration rule, and the UE is notified of the TI; alternatively, the UEis notified of the bearer identifier, and the UE directly generates theTI according to the bearer identifier, so that the TI is established inthe UE.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of establishing a PDP context by a UE in theprior art;

FIG. 2 is a flow chart of a first embodiment of a data communicationmethod according to the present invention;

FIG. 3 is a flow chart of a second embodiment of a data communicationmethod according to the present invention;

FIG. 4 is a flow chart of a third embodiment of a data communicationmethod according to the present invention;

FIG. 5 is a flow chart of a fourth embodiment of a data communicationmethod according to the present invention;

FIG. 6 is a flow chart of a sixth embodiment of a data communicationmethod according to the present invention;

FIG. 7 is a flow chart of an eighth embodiment of a data communicationmethod according to the present invention;

FIG. 8 is a flow chart of a tenth embodiment of a data communicationmethod according to the present invention;

FIG. 9 is a structural view of an embodiment of an MME according to thepresent invention;

FIG. 10 is a structural view of an embodiment of a UE according to thepresent invention;

FIG. 11 is a structural view of an embodiment of a core network elementaccording to the present invention;

FIG. 12 is a structural view of a first embodiment of an SGSN accordingto the present invention;

FIG. 13 is a structural view of a first embodiment of a PGW according tothe present invention;

FIG. 14 is a structural view of a second embodiment of an SGSN accordingto the present invention; and

FIG. 15 is a structural view of a second embodiment of a PGW accordingto the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments of the present invention provides a data communicationmethod, a communication system, and related devices, which can establisha TI in a UE and an SGSN when a bearer established in an LTE is mappedto a PDP context of a GERAN/UTRAN.

In the embodiments of the present invention, after it is determined thatthe UE has an ability to access a UTRAN or GERAN according to theobtained ability information of the UE, the TI is generated according toa pre-assigned bearer identifier and according to a preset generationrule, and the UE is notified of the TI; alternatively, the UE isnotified of the bearer identifier, and the UE directly generates the TIaccording to the bearer identifier, so that the TI is established in theUE.

The embodiments of the present invention may be categorized as followsbased on the modes for generating the TI.

A. TI Generated by an MME

In this embodiment, if a UE has the ability to access a UTRAN or GERAN(3G/2G), when the UE establishes a bearer through an EUTRAN accessnetwork, the MME assigns each TI for each bearer context of the UE, andnotifies the UE of the TI through a NAS message. The UE records the TIinformation, so as to use the TI information when accessing the 2G/3G,and the MME also needs to transfer the context to the SGSN whenperforming handover to the 2G/3G or during a routing area updatingprocess (RAU). Alternatively, the MME sends the value of the TI to theUE by carrying the value of the TI in a Session Management ConfigurationIE, or sends the value of the TI to the UE as an independent IE. A firstembodiment, a second embodiment, a third embodiment and a fourthembodiment are TI establishing processes under four scenarios.

A1. Attaching Process

In a first embodiment, as shown in FIG. 2, an attaching process of a UEin an EUTRAN is described.

In step 201, the UE sends an Attach Request message to an MME.

The Attach Request message sent by the UE carries ability information ofthe UE, in which the ability information is configured to identifywhether the UE has an ability to access a UTRAN or GERAN.

In step 202, after receiving the Attach Request, the MME triggers aseries of processing, for example, authentication, location updating,and subscription data acquisition.

In step 203, the MME creates a Default Bearer Request, and initiates adefault bearer establishing procedure to a PGW after selecting a PacketData Network Gateway (PGW) and a serving gateway (SGW).

In step 204, the SGW forwards the Default Bearer Request created by theMME to the PGW.

In step 205, after receiving the Default Bearer Request, the PGW createsa Default Bearer Response.

In step 206, the SGW forwards the Default Bearer Response created by thePGW to the MME.

Steps 203 to step 206 may be summarized as follows: After selecting thePGW and the SGW, the MME initiates the default bearer establishingprocedure to the PGW, and the PGW responds and creates a default bearerresponse message and sends it to the MME.

In step 207, the attachment is accepted.

After receiving the response message, the MME sends an Attach Acceptmessage to the UE.

The Attach Request message received by the MME carries the abilityinformation of the UE, so the MME may determine whether the UE has theability to access the UTRAN or GERAN. If the MME finds out that the UEhas the ability to access the UTRAN or GERAN, the MME assigns a value ofa TI to each bearer established by the UE, and the information is sentto the UE as an independent IE or as a part of a Session ManagementConfiguration IE. The UE receives and stores the value of the TI, anduses the value of the TI when accessing the UTRAN and the GERAN.

It should be noted that, before determining the ability information ofthe UE, the MME may obtain a bearer identifier according to the receivedattaching request message. As the UE initiates the attaching process, inthis step, the bearer identifier may be assigned by MME, and theassigned bearer identifier is obtained.

The MME generates the TI according to the obtained bearer identifier anda preset generation rule. Here, the specific generation rule is notlimited, but each TI needs to be corresponding to each beareridentifier.

It should be noted that the generation rule in this embodiment andsubsequent embodiments is configured to describe the process forgenerating the TI according to the bearer identifier, and the generationrule is a corresponding relation between the bearer identifier and theTI. The generation rule is a preset rule, and is not limited in thisembodiment and the subsequent embodiments.

In step 208, a radio bearer is established.

In step 209, the attachment is completed.

In step 210, the bearer is updated. Steps 208 to 210 may be summarizedas follows: The radio bearer is established between an RAN node and theUE, the UE sends an attach complete message to the MME, and the MMEupdates the bearer between the MME and the SGW.

In this embodiment, during the attaching procedure of the UE, the MMEmay assign the TI for the UE, so that the UE can obtain the TI. Thus,after moving to the GERAN/UTRAN, the UE can still perform normalprocessing.

A2. Dedicated Bearer Establishing Process Initiated by a PGW

In a second embodiment, as shown in FIG. 3, the dedicated bearerestablishing process initiated by the PGW is described.

In step 301, the PGW creates a Dedicated Bearer Request, and sends thededicated bearer request to an SGW.

When the network needs to initiate establishing a dedicated bearer tothe UE for data transmission, the PGW sends a dedicated bearerestablishing request message, in which the dedicated bearer establishingrequest message carries an identifier of the UE that needs to create thededicated bearer.

In step 302, the SGW forwards the Dedicated Bearer Request created bythe PGW to an MME.

Steps 301 and 302 may be summarized as follows: The PGW initiatesdedicated bearer establishment to the MME.

In step 303, after receiving the created Dedicated Bearer Requestmessage, the MME sends a Bearer Setup Request to an RAN node.

After receiving the Dedicated Bearer Establishing Request message, theMME extracts the related identifier of the corresponding UE from theDedicated Bearer Establishing request message, and obtains abilityinformation in mobility management information of the corresponding UEaccording to the identifier. The MME determines whether the UE has anability to access a UTRAN or GERAN according to the ability informationof the UE; if the MME finds out that the UE has the ability to accessthe UTRAN or GERAN, the MME assigns a value of a TI to each bearerestablished by the UE in the Bearer Setup Request message, in which theTI information may be carried as an independent IE or a part of aSession Management Configuration IE.

It should be noted that, before determining the ability information ofthe UE, the MME may firstly assign a bearer identifier according to theDedicated Bearer Establishing request message sent by the PGW, and mayalso obtain the bearer identifier related to the UE. When the UE has theability to access the UTRAN or GERAN, the MME generates the TI accordingto all the determined bearer identifiers and a preset generation rule.Here, the specific generation rule is not limited, but each TI needs tobe corresponding to each bearer identifier.

In step 304, a radio bearer is established. In this step, the RAN nodetransparently transmits the TI information to the UE through theestablishment of the radio bearer. The UE receives and stores the valueof the TI, and uses the value of the TI when accessing the UTRAN and theGERAN.

In step 305, the RAN creates a Bearer Setup Response.

In step 306, the MME creates a Dedicated Bearer Response.

In step 307, the SGW forwards the Dedicated Bearer Response created bythe MME.

Steps 305 to 307 may be summarized as follows: The RAN node returns theBearer Setup Response to the MME, and the MME creates a Dedicated BearerResponse message to the PGW.

In this embodiment, during the dedicated bearer establishing process,the MME may assign the TI to the UE, enabling the UE to obtain the TI,so that the UE can still perform normal processing after moving to theGERAN/UTRAN.

A3. Resource Requesting Process Initiated by a UE

In a third embodiment, as shown in FIG. 4, the resource requestingprocess initiated by the UE is described.

In step 401, the UE sends a Resource Allocating Request to an RAN, andthe RAN forwards the resource allocating request message sent by the UEto an MME.

In step 402, the MME forwards the Resource Allocating Request messagesent by the UE to the SGW.

In step 403, the SGW forwards the Resource Allocating Request messagesent by the UE to a PGW.

In step 404, the PGW creates a Dedicated Bearer Request, and sends theDedicated Bearer Request to the SGW; in this step, the PGW determineswhether to initiate bearer modification or to establish a new beareraccording to information in the Resource Allocating Request message; ifthe PGW determines to establish a new bearer, step 405 is performed.

In step 405, the SGW forwards the Dedicated Bearer Request created bythe PGW to the MME.

In step 406, after receiving the Dedicated Bearer Request message, theMME sends a Bearer Setup Request to the RAN node.

After receiving the Dedicated Bearer Request message, the MME extractsthe related identifier of the corresponding UE from the Dedicated BearerRequest message, and obtains the ability information in the mobilitymanagement information of the corresponding UE according to theidentifier. The MME determines whether the UE has an ability to access aUTRAN or GERAN according to the ability information of the UE; if theMME finds out that the UE has the ability to access the UTRAN or GERAN,in the Bearer Setup Request message, the MME assigns a value of a TI toeach bearer established by the UE, in which the TI information may becarried as an independent IE or a part of a Session ManagementConfiguration IE.

It should be noted that, before determining the ability information ofthe UE, the MME may firstly assign a bearer identifier according to thecreated Dedicated Bearer Request message sent by the PGW, and may alsoobtain the bearer identifier related to the UE at the same time. Whenthe UE has the ability to access the UTRAN or GERAN, the MME generatesthe TI according to all the determined bearer identifiers and a presetgeneration rule. Here, the specific generation rule is not limited, buteach TI needs to be corresponding to each bearer identifier.

In step 407, a radio bearer is established; in this step, the RAN nodetransparently transmits the TI information to the UE through theestablishment of the radio bearer. The UE receives and stores the valueof the TI, and uses the value of the TI when accessing the UTRAN and theGERAN.

In step 408, the RAN creates Bearer Setup Response.

In step 409, the MME creates Create Bearer Response.

In step 410, the SGW forwards the Create Bearer Response created by theMME.

Steps 408 to 410 may be summarized as follows: The RAN node returns aBearer Setup Response to the MME, and the MME creates a Create BearerResponse message to the PGW.

In this embodiment, during the resource requesting process, the MME mayassign the TI to the UE, enabling the UE to obtain the TI, so that theUE can still perform normal processing after moving to the GERAN/UTRAN.

A4. PDN Connection Request Process Initiated by a UE

In a fourth embodiment, as shown in FIG. 5, a flow chart of requestingthe PDN connection by the UE is described.

In step 501, the UE establishes a PDN Connectivity Request, and sendsthe PDN Connectivity Request to an RAN.

In step 502, the RAN forwards the PDN Connectivity Request establishedby the UE to an MME.

In step 503, the MME creates a Default Bearer Request and sends theDefault Bearer Request to an SGW.

In step 504, the SGW forwards the Default Bearer Request created by theMME to a PGW.

In step 505, the PGW creates a Default Bearer Response to the SGW.

Steps 501 to 505 may be summarized as follows: The UE sends a PDNConnectivity Request message to the MME, the MME initiates a defaultbearer establishing procedure to the PGW after selecting the PGW and theSGW, and the PGW responds and creates a Default Bearer Response messageand sends it to the MME.

In step 506, the SGW forwards the Default Bearer Response created by thePGW to the MME.

In the step, after receiving the created Default Bearer Request message,the MME sends a Bearer Setup Request to an RAN node.

After receiving the PDN Connectivity Request message, the MME obtainsability information of the UE from mobility management information ofthe corresponding UE, and determines whether the UE has an ability toaccess a UTRAN or GERAN according to the ability information of the UE.If the MME finds out that the UE has the ability to access the UTRAN orGERAN, in the bearer Setup Request message, the MME assigns a value of aTI to each bearer established by the UE, in which the TI information maybe carried as an independent IE or a part of a Session ManagementConfiguration IE.

It should be noted that, before determining the ability information ofthe UE, the MME may firstly assign a bearer identifier according to thecreated Default Bearer Request message sent by the PGW, and may alsoobtain the bearer identifier related to the UE. When the UE has theability to access the UTRAN or GERAN, the MME generates the TI accordingto all the determined bearer identifiers and a preset generation rule.Here, the specific generation rule is not limited, but each TI needs tobe corresponding to each bearer identifier.

In step 507, a radio bearer is established; in the step, the RAN nodetransparently transmits the TI information to the UE through theestablishment of the radio bearer. The UE receives and stores the valueof the TI, and uses the value of the TI when accessing the UTRAN and theGERAN.

In step 508, the RAN creates a Bearer Setup Response.

In step 509, the MME updates the bearer to the SGW.

Steps 508 to 509 may be summarized as follows: The RAN node returns aBearer Setup Response to the MME, and the MME updates the bearer to theSGW.

In this embodiment, during the PDN connection requesting process, theMME may assign the TI to the UE, enabling the UE to obtain the TI, sothat the UE can still perform normal processing after moving to theGERAN/UTRAN.

B. TI Generated by a Core Network Element and a UE Together

It is described in the above four embodiments that the MME generates theTI, and sends the generated TI to the UE for storage. It should beunderstood that in actual applications, after generating the TI, thecore network element (including an MME or an SGSN, the specific mode forgenerating the TI by the SGSN is described in subsequent embodiments)may not directly send the generated TI to the UE, but send a beareridentifier obtained by the core network element to the UE, and instructthe UE to generate the TI according to the bearer identifier or enablethe UE to make determination and generate the TI. The specific procedureis described in the following.

In a fifth embodiment, the process for generating the TI by the UE andthe core network element includes the following steps.

In step b1, the core network element receives a request message, andobtains ability information of the UE.

In step b2, a bearer identifier is obtained according to the requestmessage.

In step b3, it is determined whether the UE has an ability to access aUTRAN or GERAN according to the ability information of the UE; if the UEhas an ability to access a UTRAN or GERAN, the TI is generated accordingto the bearer identifier and a preset generation rule.

In step b4, the bearer identifier is sent to the UE, and the UE isinstructed to generate the TI according to the bearer identifier and thepreset generation rule, or the UE generates the TI according to thebearer identifier and the preset generation rule.

It should be noted that, the sequence of executing step b3 and step b4is not limited, and the two steps may be executed at the same time. Inaddition, the core network element may also send the generation rule tothe UE.

If the core network element does not send the generation rule, afterobtaining the bearer identifier, the UE may generate the TI according tothe preset generation rule thereof (here the generation rule needs to beconsistent with the generation rule in the core network element, and maybe determined through negotiation in advance), and the specific mode isnot limited here.

If the core network element sends the generation rule, after obtainingthe bearer identifier and the generation rule, the UE may generate theTI according to the bearer identifier and the generation rule, and thespecific mode is not limited here.

In this embodiment, the UE and the core network element (e.g. an MME oran SGSN) may generate the TI, enabling the UE to obtain the TI, so thatthe UE can still perform normal processing after moving to theGERAN/UTRAN.

In the embodiment, the UE and the SGSN/MME may generate the TI whennecessary. For example, when the UE moves to the UTRAN/GERAN or needs toinitiate a session management process in the UTRAN/GERAN, the UEgenerates the TI, and during handover to the UTRAN/GERAN or an RAUprocess, the MME generates the TI when transferring the context, andtransfers the TI to the SGSN as a part of the context.

C. TI Generated by an SGSN

In this embodiment, during the RAU process from an EUTRAN to a UTRAN orGERAN, after an SGSN obtains the context of a UE from an MME, if theSGSN finds out that a corresponding PDP context does not include TIinformation, the SGSN assigns a TI to each PDP context, and notifies theUE through an RAU accept message. The specific mode for establishing theTI under the scenario is described in the following.

In a sixth embodiment, as shown in FIG. 6, an RAU process from an EUTRANto a GERAN/UTRAN is described.

In step 601, when moving from the EUTRAN to the GERAN/UTRAN to executean RAU, a UE send an RAU request message to an SGSN.

In step 602, context request, context response, and acknowledgement areperformed between an SGSN and an MME.

Specifically, the SGSN sends a context request message to the MME, so asto request the MME to return context information related to the UE tothe SGSN.

After receiving the context request message, the MME returns thecorresponding context information to the SGSN.

In step 603, after obtaining the bearer context information from theMME, the SGSN initiates updating the bearer to an SGW and a PGW.

It should be noted that if the SGSN does not find the TI informationfrom the context information returned by the MME, the SGSN assigns a TIto each PDP context.

In step 604, the SGSN initiates location update to a home subscriberserver (HSS).

In step 605, the SGSN returns an RAU accept message to the UE, in whichthe assigned TI is carried.

The situation that the SGSN assigns the TI is described in the sixthembodiment. In actual applications, the context information of the UEneeds to be transmitted between the SGSN and the MME. Therefore, it isunderstood that in a seventh embodiment of the data communication methodof the present invention, the TI may also be assigned by the MME.

After receiving the context request message sent by the SGSN, the MMEqueries the context corresponding to the UE, and determines whether thecontext includes the TI; if the context does not include the TI, the MMEassigns the TI to each bearer context, and returns the bearer contextincluding the assigned TI to the SGSN. Then, the SGSN sends the bearercontext to the UE.

It should be noted that in the seventh embodiment of the presentinvention, the MME obtains the bearer context, and the SGSN obtains thePDP context, but the contexts are essentially the same.

In the first embodiment to the seventh embodiment of the presentinvention, the corresponding TI is generated in the UE and the SGSNthrough the same mechanism; or during the handover or the RAU process,the SGSN notifies the UE of the TI corresponding to each PDP contextthrough explicit messages; or the MME generates the TI and notifies theUE through the NAS message, so that the UE uses the TI when accessingthe 2G/3G. Therefore, when the bearer established in the LTE is mappedto the PDP context of the 2G/3G, the TI exists in the UE and the SGSN,thereby preventing the problem in the prior art.

It should be noted that in the prior art, when the UE accesses an SAEthrough the EUTRAN, the default bearer exists, and the default bearercannot be deleted, and if the default bearer is deleted, the dedicatedbearer corresponding to the default bearer will be deleted as well; whenthe UE accesses the SAE through the GERAN/UTRAN, the default bearer alsoexists, after being attached to the GERAN/UTRAN, the UE having an EUTRANability activates an interactive or background PDP context. However,when a UE of legacy (Pre-R8, the network before the 3GPP R8 version)accesses an R8 (the 3GPP R8 version) network, the UE of Pre-R8 does notknow the concept of the default bearer, thereby problems for thesubsequent operations are caused. For example, after accessing thenetwork, the UE of Pre-R8 firstly activates the dedicated bearer (a GBRbearer), thereby causing problems for the operation of the SGSN/SGW/PGW.The UE of Pre-R8 initiates deactivation of the main PDP context, and asthe main PDP context (default bearer) cannot be deleted, problems forthe operation of the SGSN/SGW/PGW will be generated as well.

Therefore, embodiment of the present invention provides a datacommunication method to solve the problems. In this embodiment, the PDPcontext establishment and the PDP context deactivation are respectivelydescribed.

A. PDP Context Establishment

In this embodiment, the process may be divided into the following typesaccording to different processing modes.

A1. An SGSN performs the processing; specifically, in an eighthembodiment, as shown in FIG. 7, a PDP context establishing processinitiated by a UE is described.

In step 701, the UE sends an Activate PDP Context Request message to theSGSN.

In this embodiment, the Activate PDP Context Request message carries aQoS parameter for activating a PDP context.

In step 702, if the SGSN determines that the UE is a UE of Pre-R8according to ability information in mobility management information ofthe UE, the SGSN converts the QoS parameter.

The specific conversion mode may be as follows: If the QoS parameter isGBR information, the SGSN may change the QoS parameter to non-GBRinformation for creating a default bearer.

In step 703, the SGW forwards the default bearer request created by theSGSN to the PGW.

In step 704, the PGW creates a default bearer response and sends thedefault bearer response to the SGW.

In step 705, the SGW forwards the default bearer response created by thePGW to the SGSN.

Steps 703 to 705 may be summarized as follows: The default bearer isestablished from the SGSN to the SGW and from the SGW to the PGW, andthe QoS parameter is modified default bearer information.

In step 706, after receiving the created default bearer responsemessage, the SGSN performs RAB assignment.

In step 707, a radio bearer is established.

In step 708, an RAB assignment response is created.

In step 709, the SGSN returns an Activate PDP Context Response messageto the UE, in which the Activate PDP Context Response message includesthe QoS parameter of the modified default bearer.

A2. A PGW Performs Processing

Difference between a ninth embodiment and the eighth embodiment lie inthat: An SGSN does not need to change a QoS parameter of GBR to a QoSparameter of a default bearer, that is, the SGSN needs not to convertthe QoS parameter, but carries a special instruction in a default bearercreating message sent to an SGW, so as to instruct the SGW that the UEis an UE of Pre-R8, and the SGW initiates default bearer establishmentto the PGW instead of rejection according to the special instruction.Similarly, the default bearer creating request message from the SGW tothe PGW also carries the special instruction, the PGW accepts the QoSprovided by the UE according to the instruction, or the PGW modifies theQoS parameter to the QoS parameter of the default bearer, that is, thePGW converts the QoS parameter, and then the PGW establishes the defaultbearer according to the QoS parameter. The special instruction may be aninstruction indicating that the UE is the UE of Pre-R8 or other similarinstructions.

In the ninth embodiment of the present invention, the PGW converts theQoS parameter, and establishes the default bearer according to theconverted parameter, or does not convert the QoS parameter, but directlyestablishes the default bearer according to the received parameter.

In the eighth embodiment and the ninth embodiment of the presentinvention, during the PDP context activation initiated by the UE, theSGSN may convert the QoS information of the non-default bearer reportedby the UE to the information of the default bearer for creating thedefault bearer, and at this time, the SGSN does not need to give thespecial instruction to the SGW and the PGW. During the PDP contextactivation initiated by the UE, the SGSN gives the special instructionto the SGW/PGW. The PGW accepts the QoS provided by the UE according tothe instruction, or the PGW modifies the QoS information to the QoSinformation of the default bearer, and gives a response to the SGSN andUE. Therefore, when the UE of Pre-R8 accesses the R8 network, theproblems in the subsequent operations of the SGSN/SGW/PGW caused by theUE of Pre-R8 not knowing some characteristics of the R8 network (forexample the default bearer) are solved. Specifically, for example, theUE of Pre-R8 does not know the concept of the “default bearer” in the R8network, so that when the UE requests to establish the bearer, the UEdoes not instruct to request to establish the default bearer. Therefore,the UE of Pre-R8 in the prior art cannot establish the default bearer inthe R8 network, so that the SGSN/SGW/PGW cannot perform the processingabout the default bearer subsequently.

In this embodiment, when the SGSN determines that the UE is a UE ofPre-R8, the SGSN converts the QoS parameter, so as to instruct the PGWto establish the default bearer, or the SGSN adds an attributeinstruction for instructing the PGW to establish the default bearer.Therefore, in this embodiment, the UE of Pre-R8 may normally establishthe default bearer in the R8 network, so that the SGSN/SGW/PGW mayperform the corresponding processing according to the default bearer.

B. PDP Context Deletion

In this embodiment, the process may be divided into the following typesaccording to different processing modes.

B1. An SGSN performs the processing.

In a tenth embodiment, a PDP context deactivation process initiated by aUE is described.

Firstly, the UE initiates a Deactivate PDP Context Request message tothe SGSN.

In this embodiment, the Deactivate PDP Context Request message carries aPDP context identifier requested to be deleted.

Next, the SGSN determines whether the UE is a UE of Pre-R8 according toability information of the UE; if the UE is a UE of Pre-R8, the SGSNdetermines whether the PDP context is a default bearer according to thePDP context identifier requested to be deleted, and if the PDP contextis a default bearer, the SGSN returns a Deactivate PDP Context Rejectmessage to the UE to reject a deleting operation of the UE.

It should be understood that, in actual applications, the SGSN may notdirectly reject the deleting operation.

In an eleventh embodiment, as shown in FIG. 8, the process includes thefollowing steps.

In step 801, a UE initiates a Deactivate PDP Context Request to an SGSN.

In this embodiment, the Deactivate PDP Context Request message carries aPDP context identifier requested to be deleted.

In step 802, the SGSN sends a Delete Bearer Request message.

If the SGSN determines that the UE is a UE of Pre-R8 according toability information of the UE, the SGSN initiates a Delete BearerRequest, and carries the PDP context identifier requested to be deletedand a special instruction which may be an instruction indicating thatthe UE is a UE of Pre-R8 or other similar instructions.

In step 803, the SGW sends a Delete Bearer Request message to the PGW inwhich the

PDP context identifier requested to be deleted and the specialinstruction are carried as well according to the trigger of the SGSN.

In step 804, according to the special instruction, if it is requested todelete the default bearer, the PGW accepts the Delete Bearer Request andreserves dedicated bearers, and creates a Delete Bearer Response.

In step 805, the SGW forwards the Delete Bearer Response.

In step 806, the SGSN sends a Deactivate PDP context Response to the UE.

It should be noted that, in this embodiment, after receiving the DeleteBearer Request message sent by the SGW, if the PGW knows that the UE isthe UE of Pre-R8 according to the special instruction, the PGWdetermines whether the bearer context is the default bearer according tothe bearer context identifier requested to be deleted, and if the bearercontext is the default bearer, the PGW deletes the default bearer, andreserves other dedicated bearers related to the default bearer.

In the above embodiment, during the bearer deleting process, the SGSNmay also initiate the bearer deleting request and carry the bearercontext identifier requested to be deleted and the special instruction.According to the trigger of the SGSN, the SGW sends the Delete BearerRequest message to the PGW, in which the PDP context identifierrequested to be deleted and the special instruction are carried.According to the special instruction, if it is requested to delete thedefault bearer, the PGW accepts the deletion request and reserves thededicated bearer related to the default bearer. Therefore, when the UEof Pre-R8 accesses the R8 network, the problems in the subsequentoperations of the SGSN/SGW/PGW caused by the UE of Pre-R8 not knowingsome characteristics of the R8 network (for example, the default bearer)are solved. Specifically, for example, in the R8 network, if the UE ofR8 requests to delete the default bearer, that is, the UE of R8 requeststo delete all the other dedicated bearers related to the default bearerat the same time, after the deletion, the UE may be separated from theR8 network. Therefore, normally, the UE of R8 does not request to deletethe default bearer, but requests to delete the dedicated bearer, but theUE of Pre-R8 does not know the concept of the “default bearer” in the

R8 network. Therefore, when requesting to delete the bearer, the UE mayrequest to delete the default bearer by mistake, and in the prior art,and the default bearer and other related bearers may be directlydeleted, so that the UE may be separated from the R8 network, which maybe not the true intention of the UE.

In this embodiment, when the bearer requested by the UE of Pre-R8 to bedeleted is the default bearer, the SGSN directly rejects the deletingrequest, so that the default bearer is not deleted, or the SGSN adds anattribute instruction, so as to instruct the PGW to delete only thedefault bearer and reserve other dedicated bearers related to thedefault bearer when the UE requests to delete the default bearer. Thus,the problem that the UE of Pre-R8 is separated from the R8 network afterthe default bearer is deleted is prevented.

Embodiments of a communication system according to the present inventionare described in the following. According to different applicationscenarios, the communication system according to the embodiments of thepresent invention may be approximately categorized as follows.

(1) A first embodiment of the communication system according to thepresent invention is corresponding to the third embodiment of themethod, and specifically includes a PGW and an MME.

The PGW is configured to receive a Resource Allocation Request messagesent by the MME, determine whether to initiate bearer modification orestablish a new bearer according to the Resource Allocation Requestmessage, and send a Dedicated Bearer Request message to the MME ifdetermining to establish the new bearer.

The MME is configured to receive the Resource Allocation Request messagesent by a UE, forward the Resource Allocation Request message to thePGW, receive the Dedicated Bearer Request message sent by the PGW,obtain a bearer identifier according to the Dedicated Bearer Requestmessage, obtain ability information of the UE, determine whether the UEhas an ability to access a UTRAN or GERAN according to the abilityinformation of the UE, generate a TI according to the bearer identifierand according to a preset generation rule if the UE has the ability, andsend the TI to the UE.

In this embodiment, the MME may assign the TI to the UE, enabling the UEmay obtain the TI, so that the UE can still perform normal processingafter moving to the GERAN/UTRAN.

(2) A second embodiment of the communication system according to thepresent invention is corresponding to the fifth embodiment of themethod, and specifically includes a core network element and a UE.

The core network element is configured to receive a request message,obtain ability information of the UE, obtain a bearer identifieraccording to the request message, determine whether the UE has anability to access a UTRAN or GERAN according to the ability informationof the UE, generate a TI according to the bearer identifier and a presetgeneration rule if the UE has the ability, and send the beareridentifier to the UE.

The UE is configured to receive the bearer identifier sent by the corenetwork element, and generate the TI according to the preset generationrule.

The core network element may be an MME or an SGSN.

In this embodiment, the core network element and the UE generate thecorresponding TI together, enabling the UE to obtain the TI, so that theUE can still perform normal processing after moving to the GERAN/UTRAN.

(3) A third embodiment of the communication system according to thepresent invention is corresponding to the eighth embodiment of themethod, and specifically includes an SGSN and a PGW.

The SGSN is configured to receive an Activate PDP Bearer Context Requestmessage sent by a UE, determine whether the UE is a UE having Pre-R8attribute according to ability information of the UE in the Activate PDPBearer Context Request message, and if the UE is a UE having Pre-R8attribute, convert a QoS parameter in the Activate PDP Bearer ContextRequest message and send the converted QoS parameter to the PGW.

The PGW is configured to receive the converted QoS parameter sent by theSGSN, and create a default bearer according to the converted QoSparameter.

In this embodiment, the PGW may create the default bearer according tothe converted QoS parameter, so that the UE of Pre-R8 may normallycreate the default bearer.

(4) A fourth embodiment of the communication system according to thepresent invention is corresponding to the ninth embodiment of themethod, and specifically includes an SGSN and a PGW.

The SGSN is configured to receive an Activate PDP Bearer Context Requestmessage sent by a UE, determine whether the UE is a UE having Pre-R8attribute according to ability information of the UE in the Activate PDPBearer Context Request message, and send a Default

Bearer Request message including attribute instruction information and aQoS parameter to the PGW if the UE is a UE having Pre-R8 attribute.

The PGW is configured to receive the Default Bearer Request message sentby the SGSN, convert the QoS parameter according to the attributeinstruction information, create a default bearer according to theconverted QoS parameter, or directly create the default bearer accordingto the QoS parameter sent by the SGSN.

In this embodiment, the PGW may convert the QoS parameter, and createthe default bearer according to the converted QoS parameter, so that theUE of Pre-R8 may normally create the default bearer.

It should be noted that, the PGW may also not convert the QoS parameter,but directly create the default bearer according to the QoS parametersent by the SGSN.

(5) A fifth embodiment of the communication system according to thepresent invention is corresponding to the eleventh embodiment of themethod, and specifically includes an SGSN and a PGW.

The SGSN is configured to receive a Deactivate Bearer Context Requestmessage sent by a UE, determine whether the UE is a UE having a Pre-R8attribute according to ability information of the UE in the DeactivateBearer Context Request message, and send a Deactivate Bearer ContextRequest message including attribute instruction information and a PDPcontext identifier to the PGW if the UE is a UE having a Pre-R8attribute.

The PGW is configured to receive the Deactivate Bearer Context Requestmessage sent by the SGSN, determine whether the PDP context identifieris a default bearer according to the attribute instruction information,and delete the default bearer and reserve a dedicated bearer related tothe default bearer if the PDP context identifier is a default bearer.

In this embodiment, the PGW may delete the default bearer according toan instruction of the SGSN, and reserve the dedicated bearer related tothe default bearer, so that the UE of Pre-R8 may normally create thedefault bearer.

Related devices according to the embodiments of the present inventionare described in the following.

Referring to FIG. 9, an MME according to the embodiment of the presentinvention includes an obtaining unit 901, a receiving unit 902, anassigning unit 903, an ability determining unit 904, and a generatingunit 905.

The obtaining unit 901 is configured to obtain ability information of aUE.

The receiving unit 902 is configured to receive a request message.

The assigning unit 903 is configured to obtain a bearer identifieraccording to the request message.

The ability determining unit 904 is configured to determine whether theUE has an ability to access a UTRAN or GERAN according to the abilityinformation of the UE, and send a determination result to the generatingunit.

The generating unit 905 is configured to generate a TI according to thebearer identifier and a preset generation rule when the determinationresult is that the UE has an ability to access a UTRAN or GERAN.

In this embodiment, the MME may further include a TI delivering unit906.

The TI delivering unit 906 is configured to send the TI to the UE.

In this embodiment, the MME may further include an identifier deliveringunit 907.

The identifier delivering unit 907 is configured to send the beareridentifier to the UE to instruct the UE to generate the TI according tothe bearer identifier and the preset generation rule.

Referring to FIG. 10, a UE according to the embodiment of the presentinvention includes an identifier receiving unit 1001, a UE side TIgenerating unit 1002, and a storage unit 1003.

The identifier receiving unit 1001 is configured to receive a beareridentifier delivered by a core network element.

The UE side TI generating unit 1002 is configured to generate a TIaccording to the bearer identifier and a preset generation rule.

The storage unit 1003 is configured to store the preset generation ruleand the generated TI.

Referring to FIG. 11, a core network element according to the embodimentof the present invention includes an RAU request message receiving unit1101, a PDP context obtaining unit 1102, a TI checking unit 1103, a TIassigning unit 1104, and a TI sending unit 1105.

The RAU request message receiving unit 1101 is configured to receive anRAU request message sent by a UE.

The PDP context obtaining unit 1102 is configured to obtain acorresponding PDP context according to the RAU request message.

The TI checking unit 1103 is configured to determine whether the PDPcontext includes a TI, and send a determination result to the TIassigning unit 1104.

The TI assigning unit 1104 is configured to assign the TI to the PDPcontext according to the RAU request message when the TI checking unit1103 determines that the PDP context does not include a TI.

The TI sending unit 1105 is configured to send the TI to the UE.

Referring to FIG. 12, a first embodiment of an SGSN according to thepresent invention includes an activation request message receiving unit1201, an attribute determining unit 1202, a converting unit 1203, and aparameter sending unit 1204.

The activation request message receiving unit 1201 is configured toreceive an Activate PDP Context Request message sent by a UE.

The attribute determining unit 1202 is configured to determine whetherthe UE is a UE having a Pre-R8 attribute according to abilityinformation of the UE in the Activate PDP Context Request message.

The converting unit 1203 is configured to convert a QoS parameter in theActivate PDP Context Request message when the UE is the UE having thePre-R8 attribute.

The parameter sending unit 1204 is configured to send the converted QoSparameter to a PGW.

Referring to FIG. 13, a first embodiment of a PGW according to thepresent invention includes a bearer creating request message receivingunit 1301, a second attribute determining unit 1302, a second convertingunit 1303, and a bearer creating unit 1304.

The bearer creating request message receiving unit 1301 is configured toreceive a Default Bearer Request message sent by an SGSN.

The second attribute determining unit 1302 is configured to determinewhether the Default Bearer Request message includes attributeinstruction information.

The second converting unit 1303 is configured to convert a QoS parameterin the Default Bearer Request message when the Default Bearer Requestmessage includes the attribute instruction information.

The bearer creating unit 1304 is configured to create a default beareraccording to the converted QoS parameter.

It should be noted that the second converting unit 1303 in thisembodiment is optional, that is, the QoS parameter may not be converted,and at this time, the bearer creating unit 1304 may directly create thedefault bearer according to the QoS parameter sent by the SGSN.

Referring to FIG. 14, a second embodiment of the SGSN according to thepresent invention includes a deleting request message receiving unit1401, a bearer determining unit 1402, a third attribute determining unit1403, and a feedback unit 1404.

The deleting request message receiving unit 1401 is configured toreceive a Deactivate PDP Context Request message sent by a UE.

The bearer determining unit 1402 is configured to determine whether aPDP context identifier in the Deactivate PDP Context Request message isa default bearer.

The third attribute determining unit 1403 is configured to determinewhether the UE is a UE having a Pre-R8 attribute according to abilityinformation of the UE in the Deactivate PDP Context Request message whenthe PDP context identifier is the default bearer.

The feedback unit 1404 is configured to return a Deactivate PDP ContextReject message to the UE when the UE is the UE having the Pre-R8attribute.

Referring to FIG. 15, a second embodiment of the PGW according to thepresent invention includes a bearer deleting request message receivingunit 1501, a second bearer determining unit 1502, a fourth attributedetermining unit 1503, and a bearer deleting control unit 1504.

The bearer deleting request message receiving unit 1501 is configured toreceive a Delete Bearer Request message sent by an SGSN.

The second bearer determining unit 1502 is configured to determinewhether a PDP context identifier in the Delete Bearer Request message isa default bearer.

The fourth attribute determining unit 1503 is configured to determinewhether the Delete Bearer Request message includes attribute instructioninformation when the PDP context identifier is the default bearer.

The bearer deleting control unit 1504 is configured to delete thedefault bearer and reserve a dedicated bearer related to the defaultbearer when the Delete Bearer Request message includes the attributeinstruction information.

Skilled person in the art should understand that all or a part of thesteps in the method according to the embodiments of the presentinvention can be implemented by a program instructing relevant hardware,and the program may be stored in a computer readable storage media. Whenthe program is run, the following steps are performed.

A request message is received, and ability information of a UE isobtained.

A bearer identifier is obtained according to the request message.

It is determined whether the UE has an ability to access a UTRAN orGERAN according to the ability information of the UE, and if the UE hasan ability to access a UTRAN or GERAN, a TI is generated according tothe bearer identifier and a preset generation rule.

The storage media may be a ROM, a magnetic disk, or an optical disk.

The data communication method, the communication system, and the relateddevices of the present invention are described in detail above. Theprinciple and implementation of the present invention are describedherein through specific examples. The description about the embodimentsof the present invention is merely provided for ease of understanding ofthe method and core ideas of the present invention. Persons of ordinaryskill in the art can make variations and modifications to the presentinvention in terms of the specific implementations and applicationscopes according to the ideas of the present invention. Therefore, thespecification shall not be construed as limitations to the presentinvention.

What is claimed is:
 1. An apparatus for data communication, wherein theapparatus is comprised in a user equipment, and the apparatus comprises:a transmitter; a receiver; a processor configured to: send, via thetransmitter, a request message to a mobility management entity (MME) ofa long term evolution (LTE) network, wherein the request messagecomprises ability information of the user equipment indicating whetherthe user equipment has an ability to access one of a UniversalTerrestrial Radio Access Network (UTRAN) and a GSM/EDGE Radio AccessNetwork (GERAN); receive, via the receiver, a transaction identifier(TI), wherein the TI is generated based on the ability information ofthe user equipment by the MME and for a bearer identifier of the userequipment in the LTE network; communicate, via the receiver and thetransmitter, with the LTE network to leave the LTE network; and performan access procedure to access, via the receiver and the transmitter, theone of the UTRAN and the GERAN by using the TI.
 2. The apparatus ofclaim 1, wherein the request message comprises one of the following: anAttach Request message initiated by the user apparatus, a Packet DataNetwork Connectivity Request message initiated by the user apparatus, aDedicated Bearer Request message initiated by a Packet Data NetworkGateway (PGW), and a Resource Allocating Request message initiated bythe user apparatus.
 3. A non-transitory computer-readable medium storinga set of instructions for data communication, the set of instructionsare used to direct a processor of a user equipment to perform acts of:send, via a transmitter of the user equipment, a request message to amobility management entity (MME) of a long term evolution (LTE) network,wherein the request message comprises ability information of a userequipment indicating whether the user equipment has an ability to accessone of a Universal Terrestrial Radio Access Network (UTRAN) and aGSM/EDGE Radio Access Network (GERAN); receive, via a receiver of theuser equipment, a transaction identifier (TI), wherein the TI isgenerated based on the ability information of the user equipment by theMME and for a bearer identifier of the user equipment in the LTEnetwork; communicate, via the receiver and the transmitter, with the LTEnetwork to leave the LTE network; and perform an access procedure toaccess, via the receiver and the transmitter, the one of the UTRAN andthe GERAN by using the TI.